<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<link rel="STYLESHEET" href="lib.css" type='text/css' />
<link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" />
<link rel='start' href='../index.html' title='Python documentation Index' />
<link rel="first" href="lib.html" title='Python library Reference' />
<link rel='contents' href='contents.html' title="Contents" />
<link rel='index' href='genindex.html' title='Index' />
<link rel='last' href='about.html' title='About this document...' />
<link rel='help' href='about.html' title='About this document...' />
<link rel="next" href="itertools-recipes.html" />
<link rel="prev" href="itertools-functions.html" />
<link rel="parent" href="module-itertools.html" />
<link rel="next" href="itertools-recipes.html" />
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name='aesop' content='information' />
<title>6.5.2 Examples </title>
</head>
<body>
<div class="navigation">
<div id='top-navigation-panel' xml:id='top-navigation-panel'>
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="6.5.1 itertool functions"
  href="itertools-functions.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></a></td>
<td class='online-navigation'><a rel="parent" title="6.5 itertools  "
  href="module-itertools.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up one Level' width='32' /></a></td>
<td class='online-navigation'><a rel="next" title="6.5.3 Recipes"
  href="itertools-recipes.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></a></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></a></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></a></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="itertools-functions.html">6.5.1 Itertool functions</a>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="module-itertools.html">6.5 itertools  </a>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="itertools-recipes.html">6.5.3 Recipes</a>
</div>
<hr /></div>
</div>
<!--End of Navigation Panel-->

<h2><a name="SECTION008520000000000000000"></a><a name="itertools-example"></a>
<br>
6.5.2 Examples 
</h2>

<p>
The following examples show common uses for each tool and
demonstrate ways they can be combined.

<p>
<div class="verbatim"><pre>
&gt;&gt;&gt; amounts = [120.15, 764.05, 823.14]
&gt;&gt;&gt; for checknum, amount in izip(count(1200), amounts):
...     print 'Check %d is for $%.2f' % (checknum, amount)
...
Check 1200 is for $120.15
Check 1201 is for $764.05
Check 1202 is for $823.14

&gt;&gt;&gt; import operator
&gt;&gt;&gt; for cube in imap(operator.pow, xrange(1,5), repeat(3)):
...    print cube
...
1
8
27
64

&gt;&gt;&gt; reportlines = ['EuroPython', 'Roster', '', 'alex', '', 'laura',
                  '', 'martin', '', 'walter', '', 'mark']
&gt;&gt;&gt; for name in islice(reportlines, 3, None, 2):
...    print name.title()
...
Alex
Laura
Martin
Walter
Mark

# Show a dictionary sorted and grouped by value
&gt;&gt;&gt; from operator import itemgetter
&gt;&gt;&gt; d = dict(a=1, b=2, c=1, d=2, e=1, f=2, g=3)
&gt;&gt;&gt; di = sorted(d.iteritems(), key=itemgetter(1))
&gt;&gt;&gt; for k, g in groupby(di, key=itemgetter(1)):
...     print k, map(itemgetter(0), g)
...
1 ['a', 'c', 'e']
2 ['b', 'd', 'f']
3 ['g']

# Find runs of consecutive numbers using groupby.  The key to the solution
# is differencing with a range so that consecutive numbers all appear in
# same group.
&gt;&gt;&gt; data = [ 1,  4,5,6, 10, 15,16,17,18, 22, 25,26,27,28]
&gt;&gt;&gt; for k, g in groupby(enumerate(data), lambda (i,x):i-x):
...     print map(operator.itemgetter(1), g)
... 
[1]
[4, 5, 6]
[10]
[15, 16, 17, 18]
[22]
[25, 26, 27, 28]
</pre></div>

<p>

<div class="navigation">
<div class='online-navigation'>
<p></p><hr />
<table align="center" width="100%" cellpadding="0" cellspacing="2">
<tr>
<td class='online-navigation'><a rel="prev" title="6.5.1 itertool functions"
  href="itertools-functions.html"><img src='../icons/previous.png'
  border='0' height='32'  alt='Previous Page' width='32' /></a></td>
<td class='online-navigation'><a rel="parent" title="6.5 itertools  "
  href="module-itertools.html"><img src='../icons/up.png'
  border='0' height='32'  alt='Up one Level' width='32' /></a></td>
<td class='online-navigation'><a rel="next" title="6.5.3 Recipes"
  href="itertools-recipes.html"><img src='../icons/next.png'
  border='0' height='32'  alt='Next Page' width='32' /></a></td>
<td align="center" width="100%">Python Library Reference</td>
<td class='online-navigation'><a rel="contents" title="Table of Contents"
  href="contents.html"><img src='../icons/contents.png'
  border='0' height='32'  alt='Contents' width='32' /></a></td>
<td class='online-navigation'><a href="modindex.html" title="Module Index"><img src='../icons/modules.png'
  border='0' height='32'  alt='Module Index' width='32' /></a></td>
<td class='online-navigation'><a rel="index" title="Index"
  href="genindex.html"><img src='../icons/index.png'
  border='0' height='32'  alt='Index' width='32' /></a></td>
</tr></table>
<div class='online-navigation'>
<b class="navlabel">Previous:</b>
<a class="sectref" rel="prev" href="itertools-functions.html">6.5.1 Itertool functions</a>
<b class="navlabel">Up:</b>
<a class="sectref" rel="parent" href="module-itertools.html">6.5 itertools  </a>
<b class="navlabel">Next:</b>
<a class="sectref" rel="next" href="itertools-recipes.html">6.5.3 Recipes</a>
</div>
</div>
<hr />
<span class="release-info">Release 2.5.1, documentation updated on 18th April, 2007.</span>
</div>
<!--End of Navigation Panel-->
<address>
See <i><a href="about.html">About this document...</a></i> for information on suggesting changes.
</address>
</body>
</html>
